Power steering pump

ABSTRACT

A power steering pump for an automotive vehicle including a housing defining a compartment, a cam plate disposed within the housing, a rotor disposed within the housing and a lower pressure plate disposed within the housing between the cam plate and a closed end of the housing. A cover sealingly engages the housing to close an open end of the housing. The cover includes under vane porting to provide a fluid path from an outlet port on the cover to the rotor.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to power steering pumps and more specifically to a power steering pump having a cover plate containing pump vane porting.

2. Description of Related Art

A power steering system used with an automotive vehicle typically utilizes a power steering pump that provides hydraulic fluid under pressure to a power steering gear assembly. The pump includes a cam plate having a cam chamber. A rotor, mounted for rotation on a shaft journaled in the housing, is located in the cam chamber. The rotor includes retractable or moveable vanes that move radially in and out depending on their location or position in the cam chamber. The cam plate is disposed between upper and lower pressure plates and located within a housing of the pump. A cover plate secures the cam plate, rotor and pressure plates within the housing.

During operation, the vehicle engine, using a belt and pulley mechanism connected to shaft journaled in the housing drives the rotor. As the rotor turns, the vanes operate to compress and discharge the pressurized fluid through fluid passageways to the outlet port and ultimately to the power steering gear assembly. At least one fluid inlet port supplies fluid to the cam chamber.

The upper pressure plate located between the cover and cam plate typically has porting or passageways that route the power steering fluid. Accordingly, the upper pressure plate cooperates with the cover to route or provide high-pressure fluid from the outlet port through under vane porting on the upper pressure plate to correspondingly distribute fluid into the cavities underneath the vanes to drive the vanes out at certain locations or positions in the cam chamber. The upper pressure plate also has porting that relieves or enables the pressure to escape and allow the vanes to retract of extend radially inward as they travel within the cam chamber.

In addition, sealing the assembly within the housing, the cover plate may include an aperture or bore that supports the shaft bushing. Accordingly, rotation of the rotor provides pressurized fluid to the fluid output port and to the cam chamber to move the rotor vanes. Due to the intricacy of the fluid ports and passageways, the cam plate and pressure plates must be accurately aligned with respect to one another in the housing whereby the cam chamber is properly aligned with the inlets and outlets to ensure proper pressure flow. To ensure a proper fit and seal it is necessary to grind the two side surfaces of the upper pressure plate and the surface of the cover. This process increases the cost of the pump and provides an additional leak path.

Therefore there exists a need for a power steering pump that utilizes a single component that combines the upper pressure plate and cover into a single piece that includes the fluid inlet and outlet porting along with the under vane porting. Such a pump reduces the number of components and potential leak paths.

SUMMARY OF THE INVENTION

The present invention provides a power steering pump for an automotive vehicle that includes a housing having a compartment. The housing includes a closed end and an open end. A cam plate is disposed within the housing. A rotor is also disposed within the housing. The rotor includes retractable vanes that cooperate with the cam plate to pressurize fluid. A lower pressure plate is disposed within the housing between the closed end and the cam plate. In accordance with the invention, a cover sealingly engages the housing at the open end to close the open end. The cover includes a side face that contacts the cam plate. The cover also includes under vane porting which provides a fluid path from an outlet port on the cover to the rotor.

In accordance with a further aspect of the invention, the under vane porting includes a fluid conduit extending between an outlet port located on the cover and at least one fluid passage located on the cover and spaced from the outlet port. Thus, the fluid conduit provides a fluid flow path between the outlet port and the fluid passage. Accordingly the cover, besides sealing the pumping components in the housing communicates high-pressure fluid from the outlet port through the under vane porting located in the cover to the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a power steering pump in accordance with the present invention.

FIG. 2 is a perspective view of a cover for a power steering pump in accordance with the present invention.

FIG. 3 is an additional perspective view of the cover of FIG. 2 taken at a different angle.

FIG. 4 is a front view of the cover for a power steering pump of FIG. 2.

FIG. 5 is an enlarged cross-sectional view of the cover of FIG. 4 taken along lines 5-5 in the direction of the arrows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a power steering pump 10, in accordance with a preferred embodiment of the present invention, for use in a power steering system of an automotive vehicle. The power steering pump 10 provides pressurized fluid to a power steering gear assembly. The pump 10 includes a housing 12 that defines a compartment surrounded by an inner wall 14 generally cylindrical about an axis 16. The housing 12 includes a closed end 18 and an open end 20 axially spaced from the closed end 18. A cam plate 22 is located in the compartment perpendicular to the axis 16. The cam plate 22 includes a cam chamber 24. A rotor 26 is disposed within the cam chamber 24. A lower pressure plate 28 is disposed within the compartment on one side of the cam plate 22 between a closed end 18 of the housing 12 and the cam plate 22. The lower pressure plate 22 and includes two diametrically opposed inlet ports and two diametrically opposed outlet ports spaced approximately an equal angular distance from the inlet ports.

The power steering pump 10 further includes a cover 30. As illustrated the cover 30 is disposed within the open end 20 of the housing 12 adjacent and contacting the cam plate 22. The outer circumferential surface 32 of the cover 30 includes a groove 34 sized to receive a seal member, such as an O-ring 36, see FIG. 1. In the disclosed embodiment, the O-ring 36 forms a seal between the cover 30 and the housing 12. A retaining ring 38 engages the housing 12 and secures the cover 30 in a secure, fluid-tight position within the housing 12.

As illustrated in FIGS. 2-4 the cover 30 includes two diametrically opposed inlet ports 40, 42 and two diametrically opposed outlet ports 44, 46.

The outlet ports 44, 46 include first 70 and second 72 portions. The portions 70, 72 are adjacent with the second portion 72 located radially outward from the first portion 70. As illustrated the first and second portions 70, 72 are grooves or channels in the planar side surface 66. The grooves or channels having opposing sidewalls 74, 76 extend axially inward into the cover 30 from the planar side surface 66.

As illustrated in FIGS. 4-5 the fluid fluid conduit 56 includes an opening 78 located on an angled surface 80 of the outlet port 44 positioned at or near the junction of the first and second portions 70, 72 of the outlet port 44. Accordingly, the fluid fluid conduit 56 extends through one of the sidewalls 74 at an angle with respect to the planar side surface 66 of the cover 30. Depending upon the angle of the fluid fluid conduit 56 a small groove or depression 82 is cut or formed in the planar side surface 66 adjacent the opposing sidewall 76.

The cover 30 also includes two pairs of passages 48, 50, 52, 54. As illustrated in FIG. 4, one pair of fluid passages 48, 50 is radially aligned with the outlet ports 44, 46 while the other pair of fluid passages 52, 54 is radially aligned with the inlet ports 40, 42. The fluid passages 48-54 are generally arcuate in shape and do not axially extend through the cover 30. Accordingly, they form a plurality of arcuate grooves located about the axis 16. A pair of passageways or fluid conduits 56 extend between the outlet ports 44, 46 and the pair of fluid passages 52, 54 that are radially aligned with the inlet ports 40, 42.

As illustrated, all of the under vane porting, including the passageway or fluid conduit 56 extending between the outlet port 44 and the fluid passage 48 is contained within the cover 30. The term under vane porting is used herein to describe the ports or passageways used to transfer or enable fluid communication with the under vane cavities located in the rotor 26. Under vane pressure is used to lift or force the vanes outward against the cam profile of the cam chamber 24 allowing the pump 10 to do work on the power steering fluid.

Depending upon the cover 30 configuration, it may be necessary to deepen or extend a portion 52 a, 54 a of the fluid passage 52, 54 further into the cover 30 such that the passageways or fluid conduits 56 connect with the respective extended portions 52 a, 54 a of the fluid passages 52, 54. For example, the portions 52 a, 54 a of the fluid passages 52, 54 may include an axially extending bore. The axially extending bore 52 a, 54 a may be necessary as use of a conventional boring tool such as a drill may limit the angle of the passageway or fluid conduit 56 with respect to the planar side surface 66 of the cover 30 based on the position of the outlet port 44 with respect to the outer circumferential surface 32 of the cover 30. In some instances it may be possible to drill or bore a passageway through the outer circumferential surface 32 of the cover 30 and into the cover 30 substantially parallel to the planar side surface 66 to connect the outlet port 44 and the fluid passage 48. However, such an assembly may be prone to leak and sealing issues and may require a plug or other seal member placed in the outer circumferential surface 32.

The fluid passages 52-54 and passageways or fluid conduits 56 are part of the under vane porting used to control the flow of fluid from the outlet ports 44, 46 to the rotor 26. As known, the rotor 26 contains a plurality of vanes that move reciprocally in radial slots located in the rotor 26. The radially outer end of each vane contacts an inner surface of the cam chamber 24. The radially inner end of each vane is located in or adjacent to a space or cavity disposed at the end of the radial slot. The space or cavity receives pressurized fluid used to urge the vane really outward against the cam surface of the cam chamber. The chambers at each end of each radial slot are aligned with and communicate with the passageways 48-54 located in the cover 30. Accordingly, fluid from the outlet ports 44, 46 travels through the passageways or fluid conduits 56 that connect the outlet ports 44, 46 with the fluid passages 52, 54. The passageways or fluid conduits 56 hydraulically connect the vanes with the outlet ports 44, 46 and allow flow of high-pressure fluid through the under vane porting to urge the vanes outward in a radial direction against the inner surface of the cam chamber 24.

The cover 30 further includes a blind bore or socket 58 forming a support structure or assembly that receives and supports the shaft 60. Accordingly, the closed end 18 of the housing 12 supports one portion of the shaft 60 while the blind bore or socket 58 located in the cover 30 also supports the shaft 60. A fluid conduit 62 connects one of the inlet ports 42 with the blind bore or socket 58. Accordingly, fluid flows from the inlet port 42 to the socket 58 to provide lubrication for the shaft 60 during pump operation. In addition, the cover 30 also includes a plurality of apertures 64 used to properly align the cover 30 and correspondingly the under vane porting with the remaining elements of the power steering pump 10 including the cam plate 22, rotor 26, lower pressure plate 28 and housing 12.

Accordingly, the present invention provides a cover 30 containing an outlet port 44, fluid passage 48 and a passageway or fluid conduit 56 extending directly from the outlet port 44 to the fluid passage 48. In this manner, the cover 30 contains the outlet port and the under vane porting. In addition, the cover 30 contains a blind bore or socket machined with clearance tolerance and flow grooves for lubrication of the pump shaft 60 whereby one end or portion of the shaft 60 is supported by the cover 30.

Accordingly, in the described embodiment, a single cover 30 is utilized to seal and secure the cam plate 22 within the housing 12 without the need for a upper pressure plate. Reducing the part count removes potential leak paths and eliminates the need for precision grinding of mating surfaces.

The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. 

1. A power steering pump for an automotive vehicle comprising: a housing defining a compartment, said housing further including an axis, a closed end and an open end; a cam plate disposed within said housing; a rotor, said rotor disposed within said housing, said rotor including retractable vanes that cooperate with the cam plate to pressurize fluid; a lower pressure plate disposed within said housing; and a cover, said cover sealingly engaging said housing at said open end to close said open end, said cover including a side face, said side face contacting said cam plate, said cover including under vane porting said under vane porting providing a fluid path from an outlet port located on said cover to said rotor.
 2. A power steering pump as set forth in claim 1 including said cover having an outer circumferential surface, said the outer circumferential surface having a groove located therein; and an O-ring located in said groove, said O-ring engaging an inner wall of said housing when said cover engages said housing.
 3. A power steering pump as set forth in claim 1 including a shaft disposed within said housing, said rotor secured to said shaft; and said cover having an axially extending bore, said bore receiving and supporting said shaft.
 4. A power steering pump as set forth in claim 3 including a fluid passage extending from at least one inlet port to said axially extending bore.
 5. A power steering pump as set forth in claim 3 wherein said under vane porting includes at least one inlet port, at least one outlet port, a plurality of fluid passages arranged about an axis of the pump; and a fluid conduit connecting and enabling fluid flow to at least one of said passages from said outlet port.
 6. A power steering pump as set forth in claim 5 including two outlet ports and two fluid passages, said fluid passages disposed radially inward of said outlet ports; and two fluid conduits 56 wherein one of said fluid conduits 56 extends from one outlet port to a fluid passage and the second fluid conduit extends from the second outlet port to the second fluid passage.
 7. A power steering pump as set forth in claim 6 including an axially extending bore located in said cover; and a fluid passage extending from said inlet port to said axially extending bore.
 8. A power steering pump as set forth in claim 1 wherein said cover includes a side surface, said side surface having a substantially planar surface, wherein at least a portion of said substantially planar surface engages said cam plate.
 9. A power steering pump as set forth in claim 1 including a pair of diametrically opposed apertures located in a side surface of said cover.
 10. A cover for use with a power steering pump for an automotive vehicle comprising: a cylindrical member having a substantially planar side surface and a circumferential outer surface; a pair of inlet ports; a pair of outlet ports; a plurality of fluid passages, said fluid passages forming spaced apart arcuate grooves located about an axis of said cylindrical member; and a fluid conduit extending between at least one of said outlet ports and at least one of said fluid passages.
 11. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including a fluid passage spaced radially inward from each outlet port and a fluid passage spaced radially inward from each inlet port; and a fluid conduit extending from said outlet port to said fluid passage spaced radially inward from said inlet port.
 12. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including said outlet ports having first and second portions, one of said first and second portion spaced radially outward from the other.
 13. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including an axial bore, and a passageway extending from an inlet port to said axial bore.
 14. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including said outlet port having first and second portions, one of said portions spaced radially outward from the other, said fluid conduit extending between of said outlet port and said fluid passage having an opening located near the junction of the first and second portions of said outlet port.
 15. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 14 including said fluid conduit extending at an angle with respect to said planar side surface of said cover.
 16. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including said fluid passage having a portion thereof extending further into said cover from said side surface, said fluid conduit extending between said outlet passage and said bore.
 17. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including said outlet port having an angled surface and an opening of said fluid conduit located on said angled surface.
 18. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 10 including a groove located in the outer circumferential surface of said cover.
 19. A cover for use with a power steering pump for an automotive vehicle comprising: a cylindrical member having a planar side surface; said cylindrical member having under vane porting, said under vane porting including at least one inlet port, at least one outlet port, at least one fluid passage; and a fluid conduit extending between said at least one outlet port and said at least one fluid passage for providing fluid flow between said outlet port and said fluid passage.
 20. A cover for use with a power steering pump for an automotive vehicle as set forth in claim 19 including an axially extending bore located in said cover and a fluid passageway extending from said inlet port to said bore. 